// convert the ip into the position in the subnet. Only
// position are saved in the set
func getPosition(address *net.IPNet, ip *net.IP) int32 {
var (
first, _ = networkdriver.NetworkRange(address)
base = ipToInt(&first)
i = ipToInt(ip)
)
return i - base
}
// return an available ip if one is currently available. If not,
// return the next available ip for the nextwork
func getNextIp(address *net.IPNet) (*net.IP, error) {
var (
ownIP = ipToInt(&address.IP)
available = availableIPS[address.String()]
allocated = allocatedIPs[address.String()]
first, _ = networkdriver.NetworkRange(address)
base = ipToInt(&first)
size = int(networkdriver.NetworkSize(address.Mask))
max = int32(size - 2) // size -1 for the broadcast address, -1 for the gateway address
pos = int32(available.Pop())
)
// We pop and push the position not the ip
if pos != 0 {
ip := intToIP(int32(base + pos))
allocated.Push(int(pos))
return ip, nil
}
var (
firstNetIP = address.IP.To4().Mask(address.Mask)
firstAsInt = ipToInt(&firstNetIP) + 1
)
pos = int32(allocated.PullBack())
for i := int32(0); i < max; i++ {
pos = pos%max + 1
next := int32(base + pos)
if next == ownIP || next == firstAsInt {
continue
}
if !allocated.Exists(int(pos)) {
ip := intToIP(next)
allocated.Push(int(pos))
return ip, nil
}
}
return nil, ErrNoAvailableIPs
}